Lubricating Composition

ABSTRACT

There is disclosed a lubricant composition comprising major amount of a base oil and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

FIELD OF THE DISCLOSURE

The present disclosure is directed to additive and lubricant compositions and methods for use thereof. More particularly, this invention is directed to an additive composition comprising (i) a triazole compound substituted with an aryl moiety, (ii) a nitrogen-containing compound, and (iii) a sulfurized compound.

BACKGROUND OF THE DISCLOSURE

Lubricating oils as used in the internal combustion engines and transmissions of automobiles or trucks are subjected to a demanding environment during use. This environment results in oxidation of the oil which is catalyzed by the presence of impurities in the oil, and is also promoted by the elevated temperatures of the oil during use.

The oxidation of lubricating oils contributes to the formation of sludge in oils and the breakdown of viscosity characteristics of the lubricant. The oxidation is often controlled to some extent by selecting the proper antioxidant additives thereby significantly improving the life of the lubricating oils. Antioxidant additives can extend the useful life of the lubricating oil by, for example, reducing or preventing unacceptable viscosity increases and/or deposit formation.

Additionally, protecting the metal surface of an engine against wear degradation by selecting the proper balance of antiwear agents in a lubricating composition can significantly increase the life of the metal surface. Antiwear agents form a thin film on metal surfaces which prevents metal to metal contact, resulting in a decrease in the amount of wear. A well-known and commonly used antiwear agent is zinc dialkyldithiophosphate (ZDDP).

However, the demanding environment in which lubricating oils are subjected, including high temperatures and/or high pressures, decompose ZDDP in a lubricating oil composition. Studies have shown that some exhaust emission catalysts may be deactivated by phosphorus, largely derived from ZDDP compounds which have been the mainstay antiwear agents in passenger car motor oil and heavy duty diesel formulations for the past 50 years. Consequently, future engine oils will contain reduced phosphorus levels. Furthermore, as ZDDP decomposes and releases zinc molecules, these zinc molecules are capable of reacting with other performance additives present in the lubricating composition, creating sludge and other particulate matter that can cause adverse effects on engine performance. These undesirable effects of oxidation present problems in meeting ever more severe engine performance requirements.

Simply lowering the amount of ZDDP is not a practical solution to the problem because of the accompanying reduction of antiwear properties. Therefore, it would be desirable for a lubricating oil composition to comprise improved additives that reduce the oxidative degradation of lubricating oils.

It has now been discovered that a composition comprising (i) a triazole compound substituted with an aryl moiety, (ii) a nitrogen-containing compound, and (iii) a sulfurized compound can provide a highly effective system which can inhibit oxidation.

SUMMARY OF THE DISCLOSURE

In accordance with the disclosure, there is provided an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

In an aspect, there is also provided a lubricant composition comprising a a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

Moreover, there is provided a method of decreasing oxidation degradation of a lubricant composition, said method comprising providing to a machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

Further, there is provided a method for operating a machine, said method comprising adding to the machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

Furthermore, there is provided a method of lubricating at least one moving part of a machine, said method comprising contacting at least one moving part with a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

Additional objects and advantages of the disclosure will be set forth in part in the description which follows, and/or can be learned by practice of the disclosure. The objects and advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure generally relates to a lubricant composition comprising major amount of a base oil and a minor amount of an additive combination comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

As used herein, the term “major amount” is understood to mean an amount greater than or equal to 50 wt. %, for example from about 80 to about 98 wt. % relative to the total weight of the composition. Moreover, as used herein, the term “minor amount” is understood to mean an amount less than 50 wt. % relative to the total weight of the composition.

As used herein, “aromatic” or “aryl”, unless expressly stated otherwise, refers to the typical substituted or unsubstituted non-aliphatic hydrocarbyl or heterocyclic moieties of this class, e.g., a polyunsaturated, typically aromatic, hydrocarbyl cyclical, or heterocyclic, substituent, which can have a single ring or multiple rings (up to three rings) that are fused together or linked covalently. Typical hydrocarbyl aromatic moieties include phenyl, naphthyl, biphenylenyl, phenanthrenyl, phenalenyl, and the like. Such moieties are optionally substituted with one or more hydrocarbyl substituents. Also included are aryl moieties substituted by other aryl moieties, such as biphenyl. Heterocyclic aryl or aromatic moieties refers to unsaturated cyclical moieties containing carbon atoms in the ring and additionally one or more hetero atoms, which are typically oxygen, nitrogen, sulfur and/or phosphorus, such as pyridyl, thienyl, furyl, thiazolyl, pyranyl, pyrrolyl, pyrazolyl, imidazolyl, pyrazinyl, thiazolyl, etc. Such moieties are optionally substituted with one or more substituents such as hydroxy, optionally substituted lower alkyl, optionally substituted lower alkoxy, amino, amide, ester moieties and carbonyl moieties (e.g., aldehyde or ketonic moieties).

As used herein, “alkaryl”, unless expressly stated otherwise, refers to an alkyl group substituted by the typical substituted or unsubstituted non-aliphatic hydrocarbyl or heterocyclic moieties described above. Typical aryl moieties include phenyl, naphthyl, benzyl, and the like. Such moieties are optionally substituted with one or more substituents such as hydroxy, optionally substituted alkyl, optionally substituted alkoxy, amino, amide, ester moieties and carbonyl moieties (e.g., aldehyde or ketonic moieties).

As used herein, the terms “hydrocarbon”, “hydrocarbyl” or “hydrocarbon based” mean that the group being described has predominantly hydrocarbon character within the context of this invention. These include groups that are purely hydrocarbon in nature, that is, they contain only carbon and hydrogen. They may also include groups containing substituents or atoms which do not alter the predominantly hydrocarbon character of the group. Such substituents may include halo-, alkoxy-, nitro-, etc. These groups also may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, sulfur, nitrogen and oxygen. Therefore, while remaining predominantly hydrocarbon in character within the context of this invention, these groups may contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms.

A triazole compound suitable for use in the compositions of the present disclosure can be any triazole, including a substituted or unsubstituted triazole compound. In some embodiments the triazole compound is a 1,2,3-triazole compound. In other embodiments the triazole compound is a 1,2,4-triazole compound. In an embodiment, the triazole compound is not an alkyl bis-3-amino-1,2,4-triazole.

As an example, the triazole compound can be substituted with a substituted or unsubstituted aryl moiety comprising a single ring or multiple rings, for example covalently linked rings. Non-limiting examples of substituted aromatic moieties comprising covalently linked rings include biphenyl, 1,1′-binaphthyl, p,p′-bitolyl, biphenylenyl, and the like. As another example, the aryl moiety can comprise multiple fused rings. Non-limiting examples of aryl moieties comprising multiple fused rings include naphthyl, anthryl, pyrenyl, phenanthrenyl, phenalenyl, and the like. As a further example, the aryl moiety can comprise a single ring covalently linked to the triazole. Non-limiting examples of aryl moieties comprising a single ring covalently linked to the triazole include phenyl and the like. As another example, the aryl moiety can comprise a single ring fused to the triazole. Non-limiting examples of aryl moieties comprising a single ring fused to the triazole include benzotriazole and tolyltriazole. An example of a commercially available triazole compound suitable for use herein is a tolyltriazole, which is a light brown powder having a melting point ranging from 80-83° C., a flashpoint of 182° C., and a boiling point of 160° C.

In an embodiment, the triazole compound can be represented by formula (II) below:

wherein R³ is selected from the group consisting of hydrogen and an alkyl moiety comprising from about 1 to about 24 carbon atoms, and wherein R⁴ is selected from the group consisting of hydrogen, an alkyl moiety comprising from about 1 to about 24 carbon atoms, and a substituted hydrocarbyl moiety. In another embodiment, R³ and R⁴ of the triazole compound represented by formula (II) can each independently comprise from about 1 to about 16 carbon atoms.

The triazole compound can be present in the disclosed lubricant and additive compositions in any effective amount, which can be readily determined by one of ordinary skill in the art. In an embodiment, the lubricating composition of the present disclosure can comprise from about 0.05 wt. % to about 0.5 wt. %, and for example from about 0.1 wt. % to about 0.3 wt. % of the triazole compound, relative to the total weight of the composition. In another embodiment, the additive composition of the present disclosure can comprise from about 0.48 wt. % to about 5 wt. % of the triazole compound, relative to the total weight of the additive composition.

The disclosed compositions can also comprise a nitrogen-containing compound for various uses. There is no particular restriction on the type of nitrogen-containing compound that can be used in the disclosed compositions of the present disclosure. Generally, a nitrogen-containing compound suitable for use herein can be represented by formula (I) below:

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono. For example, R¹ and R² can each independently comprise an aryl group comprising from about 6 to about 30 carbon atoms. Non-limiting examples of aryl groups which can comprise R¹ and R² include phenyl benzyl, naphthyl, and alkaryl. As another example, R¹ and R² can each independently comprise alkaryl, such as alkphenyl or alknaphthyl, wherein the alkyl group comprises from about 4 to about 30 carbon atoms, and for example from about 4 to about 12 carbon atoms. As still another example, R¹ and R² can each independently comprise a substituted or unsubstituted aryl group. Non-limiting examples of substituents for the aryl group can include an alkyl group comprising from about 1 to about 20 carbon atoms, hydroxyl, carboxyl, and nitro moieties. As another example, R¹ and R² can each independently be an alkyl substituted benzyl, phenyl, naphthyl.

Other non-limiting examples of nitrogen-containing compounds that are suitable include: phenylamine; diphenylamine; triphenylamine; various alkylated phenylamines, diphenylamines and triphenylamines; N,N′-bis(4-aminophenyl)-alkylamine; 3-hydroxydiphenylamine; N-phenyl-1,2-phenylenediamine; N-phenyl-1,4-phenylenediamine; dibutyldiphenylamine; dioctyidiphenylamine; dinonyidiphenylamine; phenyl-alpha-naphthylamine; phenyl-beta-naphtylamine; diheptyidiphenylamine; and p-oriented styrenated diphenylamine. Additional non-limiting examples of suitable nitrogen-containing compounds and their methods of preparation include those described in U.S. Pat. No. 6,218,576, which descriptions are incorporated herein by reference.

The nitrogen-containing compounds used herein can comprise a structure other than that shown above in formula (I) which shows but one nitrogen atom in the molecule. Thus, the nitrogen-containing compound can comprise a different structure provided that at least one nitrogen has at least one aryl group attached thereto, e.g., as in the case of various diamines having a secondary nitrogen atom as well as an aryl attached to one of the nitrogens.

The nitrogen-containing compounds used herein can have antioxidant properties in the disclosed compositions when used alone or in combination as described herein. The nitrogen-containing compounds used herein should be soluble in a final lubricant composition.

The amount of the nitrogen-containing compound in the lubricating compositions can vary depending upon specific requirements and applications. In an embodiment, the lubricating composition of the present disclosure can comprise from about 0.2 wt. % to about 1.2 wt. %, and for example from about 0.4 wt. % to about 1.0 wt. %, of the nitrogen-containing compound, relative to the total weight of the lubricating composition. In another embodiment, the additive compositions of the present disclosure can comprise from about 2 wt. % to about 12 wt. % of the nitrogen-containing compound, relative to the total weight of the additive composition.

A sulfurized compound suitable for use in compositions of the present disclosure can be any sulfurized compound provided that it is soluble in a lubricant composition. For example, the sulfurized compound can be sulfurized olefin. Non-limiting examples of sulfurized olefin include sulfurized C₄-C₂₄ alpha-olefins, sulfurized isomerized C₄-C₂₄ alpha-olefins, sulfurized branched C₄-C₂₄ olefins, sulfurized cyclic C₄-C₂₄ olefins, and combinations thereof. As another example, the oil sulfurized compound can be sulfurized fatty oil. Non-limiting examples of sulfurized fatty oil include sulfurized corn oil, sulfurized canola oil, sulfurized cottonseed oil, sulfurized grapeseed oil, sulfurized olive oil, sulfurized palm oil, sulfurized peanut oil, sulfurized coconut oil, sulfurized rapeseed oil, sulfurized sesame seed oil, sulfurized soybean oil, sulfurized sunflower seed oil, sulfurized tallow, sulfurized fish oil including herring oil and sardine oil, and combinations thereof. An example of a commercially available sulfurized compound suitable for use herein is HiTEC® 7084, available from Afton Chemical Corporation, Richmond, Va.

The sulfurized compound can be present in the disclosed lubricant and additive compositions in any effective amount, which can be readily determined by one of ordinary skill in the art. In an embodiment, the lubricating composition of the present disclosure can comprise from about 0.4 wt. % to about 1.2 wt. %, and for example from about 0.6 wt. % to about 1.0 wt. % of the sulfurized compound, relative to the total weight of the composition. In another embodiment, the additive composition of the present disclosure can comprise from about 4 wt. % to about 12 wt. % of the sulfurized compound, relative to the total weight of the additive composition.

The compositions disclosed herein can optionally contain additives, such as phosphorus-containing compounds, dispersants, ash-containing detergents, ashless-detergents, overbased detergents, pour point depressing agents, viscosity index modifiers, ash-containing friction modifiers, ashless friction modifiers, nitrogen-containing friction modifiers, nitrogen-free friction modifiers, esterified friction modifiers, extreme pressure agents, rust inhibitors, antioxidants, corrosion inhibitors, anti-foam agents, titanium compounds, titanium complexes, organic soluble molybdenum compounds, organic soluble molybdenum complexes, boron-containing compounds, boron-containing complexes, and combinations thereof. In an aspect, the phosphorus-containing compounds, for example zinc dialkyldithiophosphate salts, in a lubricant composition may be present in an amount sufficient to provide from about 100 to about 1000 parts per million by weight of total phosphorus in a lubricant composition. In another aspect, the phosphorus-containing compounds may be present in an amount sufficient to provide from about 600 to about 800 parts per million by weight of total phosphorus in a lubricant composition. In yet another aspect, the compositions can comprise various levels of at least one titanium-containing compound depending on the needs and requirements of the application.

Base oils suitable for use in formulating the disclosed compositions can be selected from any of the synthetic or mineral oils or mixtures thereof. Mineral oils include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as other mineral lubricating oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale are also suitable. Further, oils derived from a gas-to-liquid process are also suitable.

The base oil can be present in a major amount, wherein “major amount” is understood to mean greater than or equal to 50%, for example from about 80 to about 98 percent by weight of the lubricant composition.

The base oil typically has a viscosity of, for example, from about 2 to about 150 cSt and, as a further example, from about 5 to about 15 cSt at 100° C. Thus, the base oils can normally have a viscosity in the range of about SAE 15 to about SAE 250, and more usually can range from about SAE 20W to about SAE 50. Suitable automotive oils also include cross-grades such as 15W-40, 20W-50, 75W-140, 80W-90, 85W-140, 85W-90, and the like.

Non-limiting examples of synthetic oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene isobutylene copolymers, etc.); polyalphaolefins such as poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, di-nonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyl, alkylated polyphenyls, etc.); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic oils that can be used. Such oils are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene glycol having a molecular weight of about 1000-1500, etc.) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C₃₋₈ fatty acid esters, or the C₁₃ Oxo acid diester of tetraethylene glycol.

Another class of synthetic oils that can be used includes the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.) Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include those made from C₅₋₁₂ monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.

Hence, the base oil used which can be used to make the compositions as described herein can be selected from any of the base oils in Groups I-V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. Such base oil groups are as follows:

Group I contain less than 90% saturates and/or greater than 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120; Group II contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120; Group III contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 120; Group IV are polyalphaolefins (PAO); and Group V include all other basestocks not included in Group I, II, III or IV.

The test methods used in defining the above groups are ASTM D2007 for saturates; ASTM D2270 for viscosity index; and one of ASTM D2622, 4294, 4927 and 3120 for sulfur.

Group IV basestocks, i.e. polyalphaolefins (PAO) include hydrogenated oligomers of an alpha-olefin, the most important methods of oligomerisation being free radical processes, Ziegler catalysis, and cationic, Friedel-Crafts catalysis.

The polyalphaolefins typically have viscosities in the range of 2 to 100 cSt at 100° C., for example 4 to 8 cSt at 100° C. They can, for example, be oligomers of branched or straight chain alpha-olefins having from about 2 to about 30 carbon atoms, non-limiting examples include polypropenes, polyisobutenes, poly-1-butenes, poly-1-hexenes, poly-1-octenes and poly-1-decene. Included are homopolymers, interpolymers and mixtures.

Regarding the balance of the basestock referred to above, a “Group I basestock” also includes a Group I basestock with which basestock(s) from one or more other groups can be admixed, provided that the resulting admixture has characteristics falling within those specified above for Group I basestocks.

Exemplary basestocks include Group I basestocks and mixtures of Group II basestocks with Group I bright stock.

Basestocks suitable for use herein can be made using a variety of different processes including but not limited to distillation, solvent refining, hydrogen processing, oligomerisation, esterification, and re-refining.

The base oil can be an oil derived from Fischer-Tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons can be made from synthesis gas containing H₂ and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing in order to be useful as the base oil. For example, the hydrocarbons can be hydroisomerized using processes disclosed in U.S. Pat. Nos. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using processes disclosed in U.S. Pat. Nos. 4,943,672 or 6,096,940; dewaxed using processes disclosed in U.S. Pat. Nos. 5,882,505; or hydroisomerized and dewaxed using processes disclosed in U.S. Pat. Nos. 6,013,171; 6,080,301; or 6,165,949.

Unrefined, refined and rerefined oils, either mineral or synthetic (as well as mixtures of two or more of any of these) of the type disclosed hereinabove can be used in the base oils. Unrefined oils are those obtained directly from a mineral or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives, contaminants, and oil breakdown products.

According to various embodiments, there is disclosed a method of delaying the onset of viscosity increase in a lubricant composition. As used herein, the term “delaying the onset of viscosity increase” is understood to mean delaying the start of an increase in the viscosity of a lubricant composition over a period of time due to the oxidation process, as compared to a composition that is devoid of the antioxidant compositions of the present application, including a triazole compound substituted with an aryl moiety, a nitrogen-containing compound, and a sulfurized compound, as disclosed herein. The method of delaying the onset of viscosity increase in a lubricant composition can comprise providing to a machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.

According to various embodiments, there is also disclosed a method of lubricating at least one moving part of a machine. As used herein, “at least one moving part of a machine” is understood to mean at least one part of a machine which is capable of being in motion, including a gear, piston, bearing, rod, spring, camshaft, crankshaft, and the like. The method of lubricating at least one moving part of a machine comprises contacting the at least one moving part with a lubricant composition comprising a major amount of a base oil; and a minor amount of the disclosed additive composition.

In other embodiments, there is also disclosed a method for operating a machine comprising adding a lubricant composition comprising a major amount of a base oil and a minor amount of the disclosed additive composition.

The machine in the disclosed methods can be selected from the group consisting of spark ignition and compression-ignition internal combustion engines. Moreover, the at least one moving part can comprise a gear, piston, bearing, rod, spring, camshaft, crankshaft, and the like.

The lubricant composition can be any composition that would be effective in lubricating a machine. In an aspect, the composition is selected from the group consisting of passenger car motor oils, medium speed diesel engine oils, and heavy duty diesel engine oils.

EXAMPLES

The following example is illustrative of the invention and its advantageous properties. In this example, as well as elsewhere in this application, all parts and percentages are by weight unless otherwise indicated.

An antioxidant composition according to the present application was formulated comprising a triazole compound substituted with an aryl moiety, a nitrogen-containing compound, and a sulfurized compound, and a base composition, as shown in Table 1. The triazole compound employed in Example Composition 1 was a commercially available tolyltriazole (Cobratec TT-100, PMC Specialties Group, Cincinnati, Ohio). The nitrogen-containing compound was an alkylated diphenylamine (Hi-TEC® 7190, Afton Chemical Corporation, Richmond, Va.), and the sulfurized compound was a commercially available sulfurized C₁₆-C₁₈ alpha olefin (HiTEC® 7084, Afton Chemical Corporation, Richmond, Va.). A comparative example was formulated without a triazole compound, as shown in Table 2 using the same nitrogen-containing compound, sulfurized compound, and base composition as in Example 1.

TABLE 1 Example Composition 1 with Antioxidant System COMPONENT Wt. % Triazole 0.2 Aryl amine 0.4 Sulfurized olefin 0.8 Base composition Remainder WPD Rating 5.29 Viscosity 111.2% Increase

TABLE 2 Comparative Example Composition 2 COMPONENT Wt. % Triazole — Aryl amine 0.8 Sulfurized olefin 0.8 Base composition Remainder WPD Rating 2.97 Viscosity 148.5% Increase

The base composition for Example Compositions 1 and 2 included ingredients within the concentration ranges shown for Base 2 of Table 3, below. The base composition was formulated with a base stock meeting the GF-4 standards set forth by the International Lubricants Standardization and Approval Committee (ILSAC), which in the instant example, was a SAE Grade 5W-30 type motor oil. All values are stated as weight percent.

TABLE 3 Base 1 Base 2 Example Base Compositions (Wt. %) (Wt. %) Dispersant system 0.15–15    1–10 Metal Detergents 0.1–15  0.2–8   Corrosion Inhibitor 0–5 0–2 Metal Dihydrocarbyl Dithiophosphate 0.1–6   0.1–4   Antifoaming Agent 0–5 0–0.0001–0.15 Friction Modifier 0–5 0–2 Supplemental Antiwear Agents   0–1.0   0–0.8 Pour Point Depressant 0.01–5   0.01–1.5  Viscosity Modifier 0.01–10   0.25–7   Base stock Balance Balance

Sequence IIIG engine tests were performed on Example Composition 1 and Comparative Example Composition 2 using a 1996/1997 231 CID (3,800 cc) Series II General Motors V-6 fuel-injected gasoline engine. The used compositions were evaluated to determine degree of piston deposits during high temperature conditions. The degree of piston deposits was measured in terms of a weighted piston deposit (WPD) rating. The WPD rating was determined by inspection of all 6 pistons for deposit and varnish residue. The degree of piston deposit formation was evaluated according to a cleanliness code numbering 1 through 10, with 10 being considered clean. The “weighted piston deposit” result is an average of cleanliness ratings for all 6 pistons. A higher WPD rating demonstrates lower piston deposit formation and less oxidative degradation that a particular composition suffers in an engine.

The used compositions were also evaluated to determine increases in viscosity at 40° C. by well known methods in the art for measuring kinematic viscosity. The composition was sampled and analyzed every 20 hours. The greater the increase in viscosity, the less stable a particular lubricant composition is to oxidation. A lubricant composition that demonstrates a viscosity increase greater than 150% fails this criterion.

The results demonstrated the advantage of using the disclosed composition to delay the onset of viscosity increase in a lubricant composition. As shown by the foregoing example, Example Composition 1 comprising the disclosed antioxidant system demonstrated a WPD rating of 5.29 and a viscosity increase of 111.2%. In comparison, Example Composition 2 which was devoid of the disclosed composition demonstrated a WPD rating of 2.97 and a viscosity increase of 148.5%, Thus, it can be seen that the disclosed composition surprisingly and significantly reduces piston deposits with reduced increase in kinematic viscosity for lubricant compositions.

It is intended that the examples are being presented for the purpose of illustration only and are not intended to limit the scope of the invention disclosed herein. As would be understood by one of ordinary skill in the art, the particular ingredients employed and the concentrations of the ingredients can differ from those used in the examples. For instance, prophetic examples are contemplated which employ ingredients in concentrations outside of the ranges of Base 2, such as within the ranges set forth for Base 1 of Table 3, above.

It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to “an antioxidant” includes two or more different antioxidants. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or can be presently unforeseen can arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they can be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents. 

1. An additive composition comprising: (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.
 2. The additive composition of claim 1, wherein the triazole compound is substituted with a substituted aryl moiety comprising multiple rings.
 3. The additive composition of claim 1, wherein the triazole compound is substituted with a substituted aryl moiety comprising a single ring.
 4. The additive composition of claim 1, wherein the triazole compound is represented by the formula (II):

wherein R³ is selected from the group consisting of hydrogen and an alkyl moiety comprising from about 1 to about 24 carbon atoms, and wherein R⁴ is selected from the group consisting of hydrogen, an alkyl moiety comprising from about 1 to about 24 carbon atoms, and a substituted hydrocarbyl moiety.
 5. The additive composition of claim 1, wherein the sulfurized compound is selected from the group consisting of sulfurized olefins, sulfurized fatty oils, and combinations thereof.
 6. The additive composition of claim 5, wherein the sulfurized olefin is selected from the group consisting of sulfurized alpha-olefins, sulfurized isomerized alpha-olefins, sulfurized branched olefins, sulfurized cyclic olefins, and combinations thereof.
 7. The additive composition of claim 5, wherein the sulfurized fatty oil is selected from the group consisting of sulfurized corn oil, sulfurized canola oil, sulfurized cottonseed oil, sulfurized grapeseed oil, sulfurized olive oil, sulfurized palm oil, sulfurized peanut oil, sulfurized coconut oil, sulfurized rapeseed oil, sulfurized sesame seed oil, sulfurized soybean oil, sulfurized sunflower seed oil, sulfurized tallow, sulfurized fish oil and combinations thereof.
 8. The additive composition of claim 1, wherein the triazole compound is present in an amount ranging from about 0.48 wt. % to about 5 wt. %.
 9. The additive composition of claim 1, wherein the nitrogen-containing compound is present in an amount ranging from about 2 wt. % to about 12 wt. %.
 10. The additive composition of claim 1, wherein the sulfur-containing compound is present in an amount ranging from about 4 wt. % to about 12 wt. %.
 11. The additive composition of claim 1, further comprising at least one additive selected from the group consisting of phosphorus-containing compounds, dispersants, ash-containing detergents, ashless-detergents, overbased detergents, pour point depressing agents, viscosity index improving agents, ash-containing friction modifier, ashless friction modifier, nitrogen-containing friction modifier, nitrogen-free friction modifier, esterified friction modifier, extreme pressure agents, rust inhibitors, supplemental antioxidants, corrosion inhibitors, anti-foam agents, titanium compounds, titanium complexes, organic soluble molybdenum compounds, organic soluble molybdenum complexes, boron-containing compounds, and boron-containing complexes.
 12. A lubricant composition comprising: a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.
 13. The lubricant composition of claim 12, wherein the triazole compound is present in an amount ranging from about 0.05 wt. % to about 0.5 wt. %.
 14. The lubricant composition of claim 12, wherein the triazole compound is present in an amount ranging from about 0.1 wt. % to about 0.3 wt. %.
 15. The lubricant composition of claim 12, wherein the nitrogen-containing compound is present in an amount ranging from about 0.2 wt. % to about 1.2 wt. %.
 16. The lubricant composition of claim 12, wherein the nitrogen-containing compound is present in an amount ranging from about 0.4 wt. % to about 1.0 wt. %.
 17. The lubricant composition of claim 12, wherein the sulfurized compound is present in an amount ranging from about 0.4 wt. % to about 1.2 wt. %.
 18. The lubricant composition of claim 12, wherein the sulfurized compound is present in an amount ranging from about 0.6 wt. % to about 1.0 wt. %.
 19. The lubricant composition of claim 12, further comprising at least one additive selected from the group consisting of phosphorus-containing compounds, dispersants, ash-containing detergents, ashless-detergents, overbased detergents, pour point depressing agents, viscosity index improving agents, ash-containing friction modifier, ashless friction modifier, nitrogen-containing friction modifier, nitrogen-free friction modifier, esterified friction modifier, extreme pressure agents, rust inhibitors, supplemental antioxidants, corrosion inhibitors, anti-foam agents, titanium compounds, titanium complexes, organic soluble molybdenum compounds, organic soluble molybdenum complexes, boron-containing compounds, and boron-containing complexes.
 20. The lubricant composition of claim 12, wherein the lubricant composition is selected from the group consisting of passenger car motor oil, medium speed diesel engine oil, and heavy duty diesel engine oil.
 21. The lubricant composition of claim 12, further comprising at least one titanium compound.
 22. The lubricant composition of claim 12, further comprising a phosphorus-containing compound in an amount ranging from about 100 to about 1000 ppm of total phosphorus in a lubricant composition.
 23. The lubricant composition of claim 12, further comprising a phosphorus-containing compound in an amount ranging from about 600 to about 800 ppm of total phosphorus in a lubricant composition.
 24. A method of delaying the onset of viscosity increase in a lubricant composition, said method comprising: providing to a machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.
 25. The method of claim 24, wherein the machine is selected from the group consisting of spark ignition and compression-ignition internal combustion engines.
 26. A method of lubricating at least one moving part of a machine, said method comprising: contacting the at least one moving part with a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.
 27. The method of claim 26, wherein the machine is selected from the group consisting of spark ignition and compression-ignition internal combustion engines.
 28. A method of operating a machine comprising: adding to the machine a lubricating composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I):

wherein R¹ and R² are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a sulfurized compound.
 29. The method of claim 28, wherein the machine is selected from the group consisting of spark ignition and compression-ignition internal combustion engines. 